[R-390] Gear Train Removal

[Barry Scott]

Success!

TM 11-5820-357-35 (1962), at the top of page 84 (Step (50) (a) states that
S206 should be on contact 5 for MC=2 (contact 7 for MC=0 and contact 6 for
MC=1).  Once I had that in position, then rotating the KC gear eventually
brought all the cams into alignment.  Whew!

Thanks,
Barry - N4BUQ


On Wed, Sep 4, 2024 at 1:19 PM Jim Whartenby via R-390 <
r-390 at mailman.qth.net> wrote:

> Barry
> What you have experienced was a know shortcoming of the original R-390
> design and is mentioned in "Chapter 6.0 Recommendations" starting on page
> 79 of the Final Engineering Report.  Also mentioned are mechanical filters
> and tubes used that could have been upgraded if better tubes were available
> earlier in the design.  But at some point, the design work had to stop or
> it would have never left the engineering phase.  There is a point reached
> where the design is "Good Enough" aka GE.
> Relax and take a breath, nothing you have done is fatal and all can be
> corrected.  Keep us informed.
> JimLogic: Method used to arrive at the wrong conclusion, with confidence.
> Murphy
>
>     On Wednesday, September 4, 2024 at 12:43:14 PM CDT, Jacques Fortin <
> jacques.f at videotron.ca> wrote:
>
>  Ah, also forgot to mention: the RF deck have to be re-installed in the
> frame
> (see procedure chapter 59) BEFORE any re-alignment is attempted !
>
> 73, Jacques, VE2JFE in Montreal
>
> Barry, some COMMENTS imbedded in your text below.
>
> 73, Jacques, VE2JFE in Montreal
>
> Well, I don't quite know how it happened, but I can no longer get all the
> cams properly aligned.  As I mentioned, I've removed the VR counter so
> that's one point of reference that I no longer have.
>
> AH, DON'T WORRY: I HAVE DONE THE SAME FEW YEARS AGO....
>
> I had been rotating the MC change gear one click or two and then back and
> no
> problem; however, I think I lost track of which way I had rotated it and
> now
> I can't get back to where 2.000 would normally be displayed by the counter.
>
> FOR THE MC POSITION, JUST RELY ON THE ROTATING DIAL OF THE SYNC XTAL OSC
> THAT INDICATE ON WHICH MC POSITION THE SWITCHES ARE.
>
> I'll mention that I've kept the Green Gear in place and, contrary to my
> previous comment, that gear does indeed keep the MC and KC gears
> synchronized and, given that, I don't know how they're no longer where I
> can
> get them back in sync.
>
> IT DEPEND ALSO IF YOU SET THE PROPER MECHANISM POSITION CORRECTLY BEFORE
> REMOVING THE RF DECK.
> READ THE CHAPTER 59 CAREFULLY AGAIN !!!
> THEN, ROTATE THE KC SHAFT AND TRY FIRST TO ALIGN THE 8-16 MC CAM.
> IF YOU ARE LUCKY, ALL THE OTHER ONES WILL ALIGN (IF THEY WERE ALIGNED
> CORRECTLY PREVIOUSLY).
> IF NOT, TRY A FULL TURN AROUND LEFT OR RIGHT (DEPENDING THAT YOU REMEMBER
> OR
> NOT WHAT YOU HAVE DONE BEFORE).
> OR... JUST TAKE THE PROPER ALIGNMENT OF THE 8-16 mc AS THE STARTING POINT
> AND FOLLOW THE FULL CAMS RE-ALIGNMENT PROCEDURE CAREFULLY !
>
> According to the manual, as part of the complete gear teardown and rebuild
> (which I still have not decided to do), one is supposed to be able to
> rotate
> the MC gear CW (which I presume is taken to mean "CW as viewed from the
> rear"), until it hits a stop point and then, back up to the nearest notch
> which should correspond to 0.000.  My presumption is that if I back off to
> the 3rd click, that should correspond to 2.XXX and rotating the KC shaft
> should eventually get the gears (and cams) in the 2.000 position.
>
> I found that there is something that causes a "stop" at full CW and full
> CCW.  I think that stop is happening as a function of the Geneva mechanism
> and not the 10-turn stops (which aren't engaged when the RF deck is
> removed); however, CW or CCW still won't let me get the gears/cams in their
> proper setting and am wondering if I'm now truly "stuck".
>
> Any help is appreciated.
>
> Additionally, to avoid getting the transformers' cores wet, I'm removing
> the
> slug racks and transformers while cleaning the gears and, right off, I
> found
> that one of the slugs (for Z2223) was broken.  I'm sure that didn't help
> performance any.  I have it CA glued back together so that should help when
> I get this all reassembled.
>
> Thanks again,
> Barry - N4BUQ
>
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